Connector

ABSTRACT

A plug and socket type electrical connector. The socket includes a tapered pin longitudinally mounted within a sleeve to form an annular opening at one end of the socket. The mating plug includes a projection having a free end with an opening and a longitudinal slit extending through the opening. When the plug is inserted into the socket, the pin in the socket enters the opening in the free end of the plug projection and causes the projection to expand outwardly against the inside surface of the socket.

United States Patent [191 Hubner et al.

[451 July 15, 1975 i CONNECTOR [75] Inventors: Oswald Hubner, Neuenstadt; Horst Wilhelm Benker, I-Ieilbronn, both of Germany [73] Assignee: Bunker Ramo Corporation, Oak

Brook, Ill.

22 Filed: Sept. 20, 1974 211 App]. No.: 507,718

Related U.S. Application Data [63] Continuation of Ser. No. 351,594, April 16, 1973,

abandoned.

[30] Foreign Application Priority Data Apr. 18, 1972 Germany 2218751 [56] References Cited UNITED STATES PATENTS 2.125.816 8/1938 Reynolds 339/258 R 2,269,314 l/l942 MacDonald 339/256 R 2,780,792 2/1957 Earl 339/256 R 2,930,023 3/1960 Earl 339/258 R 3,253,250 5/1966 Harrison et a1. 339/258 R FOREIGN PATENTS OR APPLICATIONS 1,010,375 3/1952 France 339/252 P 190,251 7/1937 Switzerland 339/252 P 570,552 12/1957 Italy 339/258 R.

Primary Examiner.loseph H. McGlynn Attorney, Agent, or FirmNorton Lesser; F. M. Arbuckle 5 7] ABSTRACT A plug and socket type electrical connector. The socket includes a tapered pin longitudinally mounted within a sleeve to form an annular opening at one end of the socket. The mating plug includes a projection having a free end with an opening and a longitudinal slit extending through the opening. When the plug is inserted into the socket, the pin in the socket enters the opening in the free end of the plug projection and causes the projection to expand outwardly against the inside surface of the socket.

8 Claims, 4 Drawing Figures 3 8 ll ,1 I

-l I l 25 I00 28 CONNECTOR This is a continuation of application Ser. No. 351,594, filed Apr. 16, I973, abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of electrical connectors, particularly to plug and socket type connectors.

2. Description of the Prior Art An economical plug and socket type connector having a low contact resistance which remains constant during the entire lifetime of the connector has been a long term goal of connector manufacturers. To obtain such a desired electrical connection, the plug and socket must engage each other under high compressive forces which remain constant for the lifetime of the connector. Additionally, the forces acting in the axial direction which the two connector portions are joined must be constant over the entire length of the contact area to prevent localized wear and deformation of the connector portions.

Prior art connectors do not provide the high contact force necessary to obtain low contact resistance, or the force provided is not maintained constant during the lifetime of the connector. Further, forces acting upon prior art connectors during the joining or separating of the plug and socket cause deformation, lowering the contact force and decreasing the lifetime of the connector.

SUMMARY OF THE INVENTION It is an object of the invention to provide an improved plug and socket type connector. It is a further object of the invention to provide an economical connector having a low contact resistance which remains constant during the entire lifetime of the connector.

According to the invention, a socket is provided comprising a pin longitudinally mounted within a sleeve to form an annular opening at one end of the socket. The mating plug includes a projection having a free end with an opening and a longitudinal slit extending through the opening. When the plug is inserted into the socket, the pin enters the opening in the plug projection and causes the projection to expand outwardly against the inside surface of the socket. Thus the external surface of the mating plug is held under a high pressure against the inside surface of the socket.

In the present connector, the contact force is generated upon insertion of the contact plug into the socket. Even lengthy service life does not cause a substantial reduction in the initial contact pressure of the present connector. Additionally, the plug can be readily and smoothly inserted into the socket, since the forces acting in the axial direction are practically constant during the entire connecting process. Consequently, the electrical contact between the plug and socket is not interrupted during the joining process. The connector according to the invention can be used in instruments subjected to strong vibration or shock during their operation, since the contact forces are constant over the entire length of the junction.

In a preferred embodiment, the plug projection has a longitudinal slit providing at least two contact blades which spread outwardly in the radial direction when the plug is inserted into the socket and the pin in the socket engages the two contact blades. Such a connection is readily made and provides better electrical contact than connectors of the prior art utilizing expandable sleeves with a single longitudinal split.

The sleeve of the socket can be economically rollfabricated from sheet metal, and the pin can be machined or formed from bar stock. The base of the pin can be held within the sleeve of the socket by deforming the sleeve into slots or indentations in the base of the pin. A four slot configuration in the pin base can be used to hold the pin in the sleeve, since the high corn pressive forces created by this configuration prevent rotation of the pin and provide good mechanical and electrical contact.

In a preferred embodiment, the periphery of the pin has two conical portions: an end portion with a relatively steep taper adjacent the free end of the pin, and an intermediate portion with a lesser taper along the central length of the pin. A portion of the pin adjacent the base has a cylindrical periphery.

The outside diameter of the plug (in the disassembled, unstressed state) is slightly smaller than the inside diameter of the mating socket to facilitate joining the two connector portions. When the plug is inserted into the socket, the outside diameter of the plug expands due to contact of the tapered pin with the fingers forming the projection, thus providing a high contact pressure.

In the preferred embodiment, the free end ofthe plug includes a conical surface tapering inwardly toward the free end to facilitate insertion of the plug into the socket.

The plug, like the sleeve of the socket, may be rollfabricated from sheet metal. Unlike prior art connectors, the connector according to the invention is not susceptible to fatigue type failures which reduce the contact pressure between the plug and socket. Therefore, special care and special materials are not required to fabricate the new connector. For example, the parts can be readily fabricated from a bronze alloy.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in detail with reference to the accompanying drawings representing preferred embodiments of the connector according to the present invention. In the drawings:

FIG. 1 is a side view, partially in section, of the socket according to an embodiment of the invention;

FIG. 2 is an end view of the socket shown in FIG. 1;

FIG. 3 is a side view, partially in section, of a plug according to an embodiment of the invention; and

FIG. 4 is a cross-section of the plug taken along line 44 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 and 3, the connector or electrical connector assembly comprises a socket l and a plug 2. The two connector parts 1 and 2 are provided with conventional connection terminals, e.g., a crimp terminal or a soldering terminal. FIG. 1 shows a crimp terminal 3 as an example. Additionally, the two connector parts can be provided with conventional lock in means 4 for locking the parts within a suitable housing. Another feature in accordance with the prior art is stop 5 provided in plug 2 to orient the two connector parts and prevent their rotation after joining.

The sleeve 6 of socket 1 is formed as an integral part from sheet metal and has a longitudinally or axially extending split or slot therein as may be seen by reference to FIGS. 1 and 2. A pin 7 is inserted into the sheet metal sleeve in coaxial position within the sleeve. The inner end of pin 7 is provided with a flanged base 9, and the base 9 is joined to the interior of the sleeve by deforming the sleeve into a four slot indention 8 in the base 9. The pin 7 includes two conical surfaces: one surface being a first longitudinal portion or first wiping zone 10 adjacent the tapered free end of the pin has a relatively steep taper toward the free end, and a second longitudinal portion or second wiping zone being surface l0a intermediate the ends of the pin has a less steep taper. The end 11 of pin 7 adjacent the base 9 has a cylindrical surface and forms a third longitudinal portion or third wiping zone.

Plug 2 (also roll fabricated from sheet metal) includes a forward tubular projection and is provided with four axial slits 12 extending to the free end of the plug. Four finger like contact blades or resilient contact fingers 13 are provided between the slits. The contact blades 13 can spread apart in the radial direction. An opening is formed in the free end of the plug where the slits 12 intersect. The opening 15 has a diameter somewhat greater than the diameter of the tip of pin 7 in the socket 1, so that the pin can easily enter into opening 15. To further facilitate the insertion of the plug into the socket, the contact blades 13 can be tapered toward the free end. The insertable portion 14 of plug 2 opposite the free end of the plug has a cylindrical cross-section. The diameter of the cylindrical portion 14 is somewhat less than the internal cross section of the sleeve 6 of the socket 1.

When the plug 2 is joined into the socket 1, pin 7 enters into opening 15 of the plug. The conical taper on pin 7 spreads contact fingers l3 outward in the radial direction. and thereby establishes electrical contact with sleeve 6. After pin 7 has moved a short length along the inside surface of plug 2, contact fingers 13 are fully spread apart, thus providing full contact pressure. Upon further insertion of the plug into the socket, the diameter of opening '15 continues to increase as the edges of opening 15 continue to slide along the intermediate tapered portion lOa, until the cylindrical end portion 11 is reached. During the insertion operation, the outer surfaces of contact fingers 13 bear fully against the inside surface of sleeve 6. The sleeve 6 expands to accomodate the expanded fingers. As illustrated in the drawings, pin 7 is mounted longitudinally and essentially coaxially within sleeve 6. The pin 7 has a free end extending into forward portion 22 of the sleeve and arranged for receiving plug 2. Front surface 10 of pin 7 includes a taper 24 which expands from a radially small diameter adjacent the free front end 20 to a radially greater outer diameter adjacent rear portion 26 of the taper or tapered surface 24. The tapered surface 24 therefore initially engages and expands the contact fingers 13 in an initial contact wiping zone. Rearwardly of taper 24 is longitudinal portion 25 which is dimensionally at least equal to the outer dimension of portion 26 of taper 24 and includes a tapered surface or taper 28 for further expansion of fingers 13 together with cylindrical extension 30. Taper 28 expands from m a radially small diameter adjacent portion 26 to a larger radial dimension in an axially rearward direction and in combination with cylindrical extension 30, provides subsequent wiping zones for fingers 13 within the rear portion 32 of sleeve 6.

As forward projection 34 of plug 2 is inserted within sleeve 6 of socket 1, free end 36 of plug 2 is aligned by 5 free end 20 and fingers 13 are outwardly expanded by taper 24. During the insertion, free end 36 of projection 34 is spaced apart from sleeve 6 by the enlarged rear extremity 38 of taper 37 forming part of cylindrical portion 14 to facilitate alignment and entry. Thereafter, as the plug 2 advances rearwardly along tapered surface 24, the plug is expanded to engage the sleeve 6 in the first wiping zone whereafter the plug 2 engages the tapered surface 28 to further expand the plug in a second wiping zone. Continued axial movement of the plug is permitted by the slot in the sleeve which enables the sleeve to expand with the plug although under increasing radial pressure therebetween to provide excellent wiping action and electrical contact. The taper of surface 28 not being as great as the taper 24 also enables large axial movement without developing excessive radial pressure as the plug approaches cylindrical portion 30. Thus increased expansion of fingers l3 and engagement of portion 14 with sleeve 6 provides progressively increased wiping action between free end 36 of plug 2 and pin 7.

In other embodiments of the invention, the plug and socket portions of the connector can be fabricated by extrusion rather than by roll forming of sheet metal. Pin 7 can be held within the sleeve 6 of the socket by means other than the four slot indention 8 described in the preferred embodiment. Further, pin 7 can be made of a plastic material rather than a metal. Additionally, the two connector parts can be provided with conventional connecting terminals or retaining means in order to utilize the connector in available multiple contact connector housings.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An electrical connector assembly comprising:

a socket including a sheet metal sleeve having a longitudinally extending slot therein with a forward portion on said sleeve having an opening at one end and a rear portion;

a pin secured within said sleeve rear portion at a position spaced axially from said opening with a tapered free end on said pin extending into the forward portion to a position adjacent said opening and radially inwardly of said sleeve, the tapered free end of said pin including a maximum outer radial dimension spaced rearwardly from said opening to provide a first wiping zone and a longitudinal portion rearwardly of said tapered free end and dimensionally at least equal to said maximum outer dimension to provide a second wiping zone; and

a plug including a forward tubular projection of smaller diameter than the internal diameter of said sleeve for movement within said sleeve of said socket and having a free end on said projection with an opening in the free end of said projection and an outer surface taper on said projection extending longitudinally toward said free end of said projection and toward the axis of said projection, said projection being longitudinally slit from said projection opening rearwardly to form a plurality of resilient contact fingers, said plug projection insertable into said sleeve opening with said projection opening receiving said pin tapered free end for expanding said resilient fingers in said first wiping zone to wipe said plug against said sleeve and further insertion of said plug engaging said fingers with said longitudinal portion in said second wiping zone to increase the wiping action between said plug and sleeve with the slot in said sleeve enabling said sleeve to expand radially in response to engagement between said plug and sleeve to accomodate said plug.

2. The electrical connector as claimed in claim 1, wherein said pin is co-axially mounted within said sleeve, and said annular space is concentric with said sleeve.

3. The electrical connector assembly as claimed in claim 2, wherein said sleeve is fabricated of sheet metal and said pin has a base with indentations spaced axially from the free end of said pin, said pin secured in said sleeve by portions of said sleeve projecting into said indentations.

4. The electrical connector assembly as claimed in claim 2, wherein said projection is cylindrical in crosssection and said opening is co-axial with said projection.

5. The assembly as claimed in claim 1, wherein plug is fabricated from sheet metal.

6. The assembly as claimed in claim 5, wherein said sheet metal comprises bronze.

7. The electrical connector of claim 1 wherein said longitudinal portion includes a second taper longitudinally extending rearwardly and outwardly at a lesser slope than the slope of said taper with said free end.

8. The electrical connector of claim 7 wherein said longitudinal portion includes a cylindrical section rearwardly of said second taper, the combination of said first and second tapers and said cylindrical section providing three wiping zones of progressively increased wiping action. 

1. An electrical connector assembly comprising: a socket including a sheet metal sleeve having a longitudinally extending slot therein with a forward portion on said sleeve having an opening at one end and a rear portion; a pin secured within said sleeve rear portion at a position spaced axially from said opening with a tapered free end on said pin extending into the forward portion to a position adjacent said opening and radially inwardly of said sleeve, the tapered free end of said pin including a maximum outer radial dimension spaced rearwardly from said opening to provide a first wiping zone and a longitudinal portion rearwardly of said tapered free end and dimensionally at least equal to said maximum outer dimension to provide a second wiping zone; and a plug including a forward tubular projection of smaller diameter than the internal diameter of said sleeve for movement within said sleeve of said socket and having a free end on said projection with an opening in the free end of said projection and an outer surface taper on said projection extending longitudinally toward said free end of said projection and toward the axis of said projection, said projection being longitudinally slit from said projection opening rearwardly to form a plurality of resilient contact fingers, said plug projection insertable into said sleeve opening with said projection opening receiving said pin tapered free end for expanding said resilient fingers in said first wiping zone to wipe said plug against said sleeve and further insertion of said plug engaging said fingers with said longitudinal portion in said second wiping zone to increase the wiping action between said plug and sleeve with the slot in said sleeve enabling said sleeve to expand radially in response to engagement between said plug and sleeve to accomodate said plug.
 2. The electrical connector as claimed in claim 1, wherein said pin is co-axially mounted within said sleeve, and said annular space is concentric with said sleeve.
 3. The electrical connector assembly as claimed in claim 2, wherein said sleeve is fabricated of sheet metal and said pin has a base with indentations spaced axially from the free end of said pin, said pin secured in said sleeve by portions of said sleeve projecting into said indentations.
 4. The electrical connector assembly as claimed in claim 2, wherein said projection is cylindrical in cross-section and said opening is co-axial with said projection.
 5. The assembly as claimed in claim 1, wherein plug is fabricated from sheet metal.
 6. The assembly as claimed in claim 5, wherein said sheet metal comprises bronze.
 7. The electrical connector of claim 1 wherein said longitudinal portion includes a second taper longitudinally extending rearwardly and outwardly at a lesser slope than the slope of said taper with said free end.
 8. The electrical connector of claim 7 wherein said longitudinal portion includes a cylindrical section rearwardly of said second taper, the combination of said first and second tapers and said cylindrical section providing three wiping zones of progressively increased wiping action. 